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WASHINGTON (Reuters) - It made a big splash when scientists announced in 2006 that images from a NASA spacecraft indicated water apparently had flowed on the surface of Mars in the past decade but new research casts doubt on that finding.
The High Resolution Imaging Science Experiment (HiRISE) on board NASA's Mars Reconnaissance Orbiter (MRO) observed what appeared to be fresh gullies formed by a rapid release of water on the Martian surface in 2006. However, new computer models simulating the creation of gullies on the surface of Mars suggest that they are in fact created by the flow of dry debris (i.e. landslides) and not by the flow of water. A blow for the microbial life hunters and a huge blow for mission planners looking for easy sources of water for manned missions…
The MRO isn't the only orbiter to view apparent gullies forged by spurts of water. The Mars Orbiter Camera (MOC) onboard NASA's Mars Global Surveyor (MGS) also made news in 2006 when scanning the cratered regions of Terra Sirenum and Centauri Montes. Images taken several years apart revealed some changes in the most recent pictures, highlighting what looked like outflow channels from surges of liquid water (pictured below). What made this especially exciting was that this was possible evidence for the existence of liquid water flowing on Mars within the past few years (albeit very quickly).
On hearing the news in 2006 that there was a possibility of liquid water flowing on the Martian surface, biologists hoped that a new tool had been found to pinpoint where sub-surface deposits of liquid water may be stored. This will have provided future missions with a location to hunt for life in the most likely place, near fresh gullies, near a source of water. Unfortunately it seems that these gullies are in fact shaped by small landslides, not by surges of water from a sub-surface reservoir.
Research to be published in the March issue of Geology, entitled: "Recent bright gully deposits on Mars: wet or dry flow?".